Reverse flow check valve in hydraulic valve with series circuit

Abstract

A valve assembly includes a valve body having at least a first bore and a second bore, a flow passage connecting the first bore to the second bore, a plurality of ports opening to each bore respectively, the first bore being upstream of the second bore. First and second spools are disposed in the first and second bores, respectively, for controlling the flow of fluid to and from the respective ports. A check valve is disposed in the flow passage and configured to prevent fluid flow from the second spool towards the first spool through the flow passage while allowing fluid flow from one of the ports in the first bore towards the second spool through the flow passage.

What is claimed is: 
     
       1. A valve assembly including:
 a valve body having at least a first bore and a second bore, a plurality of ports opening to each bore respectively, the first bore being upstream of the second bore; 
 first and second spools disposed in the first and second bores respectively for controlling the flow of fluid to and from the respective ports to selectively operate respective first and second functions; 
 the first spool being configured, when in an activated position, to direct fluid from one work port to the first function to move the first function and to direct fluid displaced by the first function to an opposite work port; 
 a flow passage connecting the opposite work port to the downstream second bore to direct fluid displaced by the first function to the second bore and create a series circuit between the first function and the downstream second function; and 
 a check valve disposed in the flow passage and configured to prevent fluid flow from the second spool towards the opposite work port in the first bore through the flow passage while allowing fluid flow from the opposite work port in the first bore towards the second spool through the flow passage; 
 wherein the first function includes a first movable member of construction or industrial equipment and wherein the second function includes a second movable member of construction or industrial equipment. 
 
     
     
       2. The valve assembly according to  claim 1 , wherein the valve body further includes a third bore downstream of the second bore and a second flow passage connecting the second bore to the third bore. 
     
     
       3. The valve assembly according to  claim 2 , further including a third spool disposed in the third bore and a second check valve disposed in the second flow passage and configured to prevent fluid flow from the third spool towards the second spool through the second flow passage while allowing fluid flow from one of the ports in the second bore towards the third spool through the second flow passage. 
     
     
       4. The valve assembly according to  claim 1 , wherein the valve body includes a third bore through the flow passage for receiving the check valve. 
     
     
       5. The valve assembly according to  claim 4 , wherein the check valve includes a third spool biased in a closed position by a resilient member to prevent fluid flow through the flow passage and being movable by upstream pressure to an open position allowing fluid flow through the flow passage. 
     
     
       6. The valve assembly according to  claim 5 , further including a cap secured to the valve body to close the third bore, wherein the third spool is biased against the cap in the closed position. 
     
     
       7. The valve assembly according to  claim 1 , wherein the check valve is a spring biased closed poppet/seat check or a spring biased closed moving spool. 
     
     
       8. The valve assembly according to  claim 1 , wherein the valve body is monocast. 
     
     
       9. A method of forming the valve assembly according to  claim 1 , the method including machining a third bore in the valve body that is larger in diameter than a width of the flow passage and perpendicular to the path of fluid flow, the third bore being above and below the passage. 
     
     
       10. The method according to  claim 9 , further including inserting the check valve in the third bore such that a third spool of the valve resides in the third bore above and below the passage thereby blocking the passage. 
     
     
       11. A valve assembly including:
 a valve body having at least a first bore and a second bore, and one or more ports opening to each bore respectively, the first bore being upstream of the second bore; 
 upstream and downstream spools disposed in the first and second bores to selectively activate respectively a first upstream function and a second downstream function; 
 a downstream feed passage connecting the first bore to the second bore to direct fluid displaced by the first upstream function from one of the ports opening to the first bore to one of the ports opening to the second bore and to create a series circuit between the first upstream function and the second downstream function; and 
 a check valve disposed in the downstream feed passage to prevent reverse motion to the first upstream function connected to the one or more ports opening to the first bore when the second downstream function connected to the one or more ports opening to the second bore is activated; 
 wherein the first upstream function includes a first movable member of construction or industrial equipment and wherein the second downstream function includes a second movable member of construction or industrial equipment.